Cuban-born photographer Abelardo Morell demonstrated the concept of camera obscura to college students in 1988 by turning the entire classroom into a camera.

On a sunny day, he covered the classroom windows with black plastic, making the space as dark as a cave, cut a dime-size hole in the material, and told his students to watch. Almost instantly the back wall came alive like a movie screen, its surface covered with a fuzzy image of people and cars moving along Huntington Avenue outside. Then the double take: The image was upside down, sky on floor, ground on ceiling, the laws of gravity seemingly gone haywire.

Morell had turned his classroom into a camera obscura, a dark chamber, the Latin name for perhaps the earliest known imaging device and the ancestor of the photographic camera.

Explaining the optical principle behind the device is probably the most complicated thing about it. A camera obscura receives images just like the human eye—through a small opening and upside down. Light from outside enters the hole at an angle, the rays reflected from tops of objects, like trees, coursing downward, and those from the lower plane, say flowers, traveling upward, the rays crossing inside the dark space and forming an inverted image.

Morell developed a way to photograph the images made with his homemade cameras obscura, whether they were created with a box, a room, or even a tent. Link to story. Link to photo gallery. -Thanks, Marilyn!